The subject matter described herein relates generally to electrical connectors and, more particularly, to electrical connectors having a resistor.
Existing electrical connectors include ground contacts and power contacts extending therefrom. The power contacts are configured to carry electrical power between the connector and a corresponding mating connector. Generally, connectors and mating connectors are coupled when the power signal is inactive. Accordingly, such “cold mating” does not present problems with power surges across the connectors. However, some connectors and mating connectors may be “hot mated” at a time when a power signal is flowing through one or more of the connectors. Whenever more than a few volts and/or a few amps are available to an interconnection as it is separated or mated, there can be damage to the contacts and connector as well as risk to the operator if the energy is sufficiently high. In spite of this risk, there are many situations that require hot mating between connectors.
Some existing connectors utilize an auxiliary contact with a series PTC (positive temperature coefficient) device. The PTC device can provide protection against damaging results when separating energized DC circuits with inductive and resistive loads. In such a device, a ground contact carries the main current and makes the connection first and separates last. A power contact is the second main current carrying member and makes the connection last and separates first. The auxiliary contact is in series with the PTC device. The auxiliary contact and the PTC device are in parallel with the main power contact. The auxiliary contact provides an intermediate timed connection and separation. As the connector is separated, the main power contact separates first. There is essentially no voltage across this interface as it separates because the voltage is shunted by the auxiliary contact and PTC device. Without sufficient voltage difference, there can be no arcing and therefore no contact damage. During the time the connector continues to separate but before the auxiliary contact separates, the PTC device switches to a high resistance state because the load current now flows through the PTC device. When the auxiliary contact finally separates there is no current flowing through the connection, again preventing a damaging arc at the interface. This arrangement provides protection against the severely damaging plasma arc that can develop at a separating energized interface. This is true for all resistive and inductive loads.
However, PTC devices do not provide protection for systems with capacitive loads. For capacitive loads a significant voltage difference is not normally encountered at separation. With inductive and resistive loads there is generally little damage to the contacts if they have sufficient mass and are mated at an adequate velocity. Existing connector designs provide adequate protection for inductive and resistive loads during separation and mating, but do not provide adequate protection from capacitive loads during mating.
A need remains for a connector that can be hot mated to a mating connector supplying a capacitive load without damaging the contacts or connector.